1. Technical Field
The present disclosure relates generally to linear sortation conveyors, also known as shoe sorters, and their components, and is particularly directed to dual sided shoe sorters.
2. Description of the Related Art
Sortation conveyors are essential components of high volume distribution and fulfillment operations. A sortation conveyor system typically conveys and distributes articles along moving conveyor surfaces, and diverts selected articles onto a particular conveying branch. Sortation conveyors often employ a plurality of pusher elements which may be selectively moved across the conveying surface in order to divert an article from the primary conveying path and onto a secondary conveying branch. Sortation conveyors have a primary conveying surface which can comprise an endless conveyor belt loop formed from plurality of transverse rollers or slats. When it is necessary to direct an article from the moving conveying path and onto a secondary conveying branch, a switch or switch mechanism is actuated to cause an assigned set of pusher elements to be diverted across the moving conveyor surface. The transversely diverted pusher elements engage the article to the secondary conveying branch, such as a takeaway conveyor. Sortation conveyors often use divert tracks or guide surfaces which direct the assigned set of pusher elements laterally across the conveying surface, while pusher elements which are not assigned pass by the divert tracks and continue to travel along the conveying surface in their set position.
Dual sided shoe sorters can provide a higher density sortation solution with each side of the sorter acting as a single sided shoe sorter that is fed from respective induction conveyors. However, such generally known dual sided shoe sorters such as described in U.S. Pat. No. 6,478,144, the disclosure of which is hereby incorporated by reference, require pre-sorting and separate conveyance of article to respective sides of the dual sided shoe sorter.
During the 1980s, UNISORT 5 sorter by Applicant's predecessor the Buschman Company, Cincinnati, Ohio, employed a single center induct that supplied a dual sided shoe sorter. The straight angled pre-sort switches and guides necessarily had to operate at about 300 fpm or less, a low speed by today's stands. This speed limitation was also imposed on the divert switches and guides that also were straight angled. Higher speed operation would cause great variability in the lateral placement during pre-sort of articles such as totes and cartons during pre-sort, depending on weight, friction, etc. High speeds during the divert tended to impact and tumble the articles.
Higher speed linear sortation conveyors can provide for greater throughput. U.S. Pat. No. 7,516,835 B2 (“Soft Touch Patent”), the disclosure of which is hereby incorporated in its entirety, provides a high speed sliding shoe sortation conveyor. A divert guide is configured to guide shoes or pushers to engage articles disposed on an endless conveying surface at an initial impact which does not result in an out of control situation even at high speeds. The divert guide path is disposed at a plurality of divert angles, and guide pushers to engage articles at a low initial contact divert angle and first lateral speed and to accelerate the articles to a final divert angle and second, higher, lateral speed. The pushers may be undergoing lateral acceleration at the time initial contact is made with the articles. Articles are inducted onto the endless conveyor surface close to the pushers so that the pushers initially contact a selected article at relatively low lateral speed and then smoothly accelerate the article to the divert location.